Method of making ball studs



May 29, 1962 B. E. RICKS 3, 6

. METHOD OF MAKING BALL STUDS Filed Dec. 25, 1957 E22 saw/m0 z. xe/c/ns'lathe cutting steps.

United States Patent 3,036,366 METHOD OF MAKING BALL STUDS Bernard E.Ricks, Birmingham, Mich., assignor to Thompson Ramo Wooldridge Inc., acorporation of Ohio Filed Dec. 23, 1957, Ser. No. 704,460 12 Claims.(Cl. 29-1495) The present invention relates broadly to the art of metalforming, and is more particularly concerned with a new and improvedmethod of making ball studs by punch and die extrusion techniques.

Current production methods in the forming of ball studs requirerelatively expensive and time consuming Applicant, however, hasdiscovered that a superior article may be provided by utilizing punchesand dies to successively shape a blank into a finished stud. Brieflystated, the present method comprises providing a blank of predetermineddiameter and length from coil stock or the like, locating the blank inalignment with a die having a cavity corresponding to the outer shape ofthe final stud with the exception of the entire head thereof, anddirecting against one end of the blank a first punch to provide uponsaid blank the stem, taper, shank and portion of the head ultimatelydesired. At least one additional punch is then directed at the center ofthe partially shaped head to form a thimble-shaped cavity therein, andthis is followed by use of a diehav-ing a concave cavity which forms thestud head into the desired ball-shaped configuration. The thimble-shapedrecess is thereby converted into an essentially round inner cavity inthe head, providing a lubricant reservoir for the tie rod socket orother structure within which the ball stud is normally received.

It is therefore an important aim of the present invention to avoid thedisadvantages of prior art processes by the provision of a ball studforming method which may be accomplished with a limited number ofpunches and dies utilizing a relatively few readily performed steps.

Another object of the invention is to provide a method of making ballstuds which may be performed utilizing existing punch press or coldheader equipment, and does not require the relatively expensive andtime-consuming earlier steps of blanking, machining and grinding.

Another object of the invention lies inthe provision of a ball studforming method which speedily and effectively produces a superiorproduct having a permanently lubricated reservoir therein.

A further object of the present invention is to provide a novel methodof making ball studs which does not require a final finishing operation,and which comprises first forming upon a blank of predetermined size,the stem, taper, shank and portion of the head thereof, producing in thehead a generally thimble-shaped cavity, and forming the exterior of thehead portion into the ballshaped configuration desired.

Other objects and advantages of the present invention will become moreapparent as the description proceeds particularly when taken inconnection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate likeparts throughout the same.

FIGURE 1 is a view of a typical blank from which the finished ball studmay be formed;

FIGURE 2 is a sectional view of a first forming die showing the studblank being directed therein by the first punch member;

FIGURE 3 is a sectional view of a second die showing the partiallyformed ball stud as produced by the step of FIGURE 2 and prior toinitial formation of a head cavity and further shaping of the head bythe punch member of FIGURE 3;

3,036,365 Patented May 29, 1962 FIGURE 4 is a sectional view of a thirddie showing a relatively shallow concave head cavity as provided by thestep of FIGURE 3 and prior to further shaping of the head and cavitytherein by the punch member of FIGURE 4;

FIGURE 5 is a sectional view of a fourth die showing the ball stud headas formed by the step of FIGURE 4, and a female die member which may beutilized to shape the ball stud head into the final round configuration;and

FIGURE 6 is a view partially in section, of the finished ball studshowing the head cavity and passage thereto as formed by the step ofFIGURE 5.

Referring now to the drawings, and initially first to. FIGURE 6 thereof,a full ball stud 10 as produced in, accordance with this inventioncomprises a stem 11 of generally uniform diameter which ultimately maybe threaded by cutting or rolling, and one or more tapered port-ions 12and 13 having diameters greater than that of the stem 11. Integral withthe tapered portions is a shank 14 of generally uniform cross-sectionthroughout its length and upon which an integral head 15 is received.The head is generally circular in cross-section, as shown,

'and is provided interiorly thereof with a substantially round cavity 16connecting with a slender open-ended passage 17 located in generally thecenter of thetop of the head portion. The passage 17 provides a flowpath for lubricant into and out of the cavity 16, and said cavitythereby constitutes an eifective grease reservoir that can be drawn uponthroughout the life of the tie rod socket or other structure with whichthe ball stud 10 is associated. When ball studs are manufactured bycustomary lathe cutting operations, the head of a ball stud iscompletely closed, and provision of the cavity 16 provides a means bywhich the life of the tie rod socket or other structure may besubstantially increased.

As indicated previously, it has heretofore been customary in the art toform full ball studs by a series of relatively expensive andtimeconsuming steps of blanking, machining and grinding the part frombar stock in which much time and material is wasted in the long cutingoperation. Applicant has discovered that much time can be saved and amore effective article produced by moving the metal rather than cuttingthe same. Turning now to FIGURE 1, the first step in the present processis the provision of a length of blank material which may be cutcontinuously from coil stock to the desired diameter and length.Designated as 18, the blank is then located adjacent and in alignmentwith a die 19 having the internal configuration shown. Within the diethere is provided a cavity designated in its entirety by the numeral 20,and corresponding to the outer shape essentially of the ball stud 10,with the exception of the ultimate head portion 15 thereof.Specifically, the cavi ty includes a beveled shoulder 21 against whichis formed the beveled end 22 on the stud 10, and a section 23 ofrelatively uniform diameter which provideswhen the blank 18 is extrudedthereagainst the stem 11 of the stud. Outwardly of the cavity 20 fromthe section 23 are tapered sections 24- and 25 which form the portions12 and 13 on the stud. It will, of course, be appreci ated that forcertain applications in practice only a single taper on the stud isrequired, and accordingly, the die cavity design would be suitablymodified to take this into consideration.

Corresponding in outer diameter to the shank 14- is a section 26 of thecavity, and at the outer or upper end of the cavity 20 is a section 27of semi-circular shape in cross-section corresponding in radius toapproximately the lower half portion of the 'fully rounded head 15,shown in FIG. 6.

The blank 18 need not be heated prior to insertion into the die cavity20, or prior to the succeeding steps and the cold heading or coldextruding made possible by this invention was quite un'foreseeable.Thus, heretofore it was believed that forward and backward extrusion, ina cold heading die, was impossible to achieve. Yet the present inventionproduces such movement of metal without either heating the die or themetal.

A, punch 28 having a recessed portion 29 at one end thereof'ispreferably employed to extrude the blank 18 into the desired initialshape, and upon completion of full travel of said punch 28, there isformed the beveled end 22, stem 11, tapers 12 and 13, shank 14 andapproximately one-half of the head 15 shown in FIG. 3 in the partiallyformed condition. In addition, when the blank 18 is driven completelyinto the cavity 20, the extent of which at one end is a shoulder 30adjacent the knockout hole 31 of the die, there is provided on thepartially shaped head portion of the stud a raised portion 32corresponding to the slightly concave recess 29 in the punch head 28.The recess in said first punch could of course be eliminated; however,its use has been found desirable in actual 'practicein order to assistin controlling sideward movement of the blank 18, and is preferred forthis and other reasons.

Upon completion of the step shown in FIGURE 2, the stem, taper and shankportions are'essentially finally formed. To then further shape the headinto its ultimate fully round configuration, a punch 33 having a convexshaping surface 34 may be employed. A die 35' having a'somewhat deeperhead cavity 36 is preferably provided, and after location therein of thepartially forined stud 37 from FIGURE 2, the punch 35 is drivenforwardly and against the raised portion 32. There is formed by thisaction a generally concave recess 38, as shown in FIGURE 4, and whichcorresponds to the con vex shaping surface 34 on the punch 33.

To further shape the head of the partially iformed stud 39 from FIGURE3, said stud is preferably located in a die 40 (FIGURE 4) which differsfrom the die 35 in the increased depth of its head cavity 41. A punch 42having a shaping surface 43 of generally thimbleshaped configuration isthen moved forwardly into the cavity 41 and into the head recess 38provided therein by the step of FIGURE 3. As the shaping surface 43 ofthe punch 42 continues forwardly into the partially shaped head of thestud 39, the head material surrounding'said shaping surface is forcedoutwardly in the head cavity 41 of the die 40 in contact with the wallsthereof. Upon reaching the end of travel of the punch 42, thehead-portion of the stud 39 is provided therein with a thimble-shapedcavity 44, as appears in FIGURE 5, said cavity conforming to thecurvature of the shaping surface 43.

To accomplish the final forming step of FIGURE 5, in which the head isshaped into its fully round or ballshaped configuration, the stud shape45 from the step of FIGURE 4 may be transferred to a die 46 having ahead section cavity 47 which'is of lesser depth than the cavity 41of die40. While supported in said die 46, there is directed against thestud-shape-45 a female die 48 having a substantially concave shapingsurface 49 provided therein. As relative movement between the dies 46and 48 occurs, the outer walls of the partially shaped head arein effectsurrounded by the shaping surface 49 of the die 48, and caused to rollradially inwardly thereon. This transforms the generally thimble-shapedcavity 440i the shape 45 into a substantially round cavity 16 as appearsin the finally'shaped ball stud of FIGURE 6.

Apparatus of varying types may be'employed with the dies and punchesshown in the drawings to expeditiously form the full ball stud ofFIGURE6. As for example, a progressive three blow cold header having threeworking blows in addition to the cutofi mechanism could be employed topractice the steps of FIGURES 2, 3 and 4. 7 Final shaping of the head,as shown in FIG- URE 5, could then be performed as'a secondary opera- 4tion with a second single blow cold header, or a punch press, either ofwhich could be automatically hoppered for continuous operation. On theother hand, a cold header provided with an oscillating head whichpermits two punches of different form to alternately strike the same diecould be effectively utilized. Thus, utilizing the combination of aprogressive header, that is, a threeblow machine, with an oscillatinghead, it would be practical with one machine to perform each of thesteps shown in FIGURES 2 through 5. As, for example, punches 28 and 33could alternately strike the blank 18 which would remain in die 19 andthe progressive operation continued to die 40 and punch 42, and then tothe final finishing operation employing dies 46 and 48. It will thus beappreciated that the step of FIGURE 3 may not at all times'be required,and that formation of the ball stud 10 may be effectively accomplishedonly by the steps of FIGURES 2, 4, and 5. In addition, by the provisionof die inserts, it is believed possible to use only a single master die.

It may now be seen that applicant has provided a novel method of makingfull ball studs which may be speedily and effectively accomplished withthe minimum amount of equipment. The final product as produced by thesteps herein disclosed has the important advantage of permanentlubricating properties not possessed by prior art structures, and thesteps performed in providing such an article are considerably fewer innumber and less laborious than'methods heretofore practiced. Arelatively small number of simply constructed dies and punches may beemployed, and the earlier expensive steps of blanking,

.machining and grinding are no longer required. Further,

the method of this invention is much more readily adapted to massproduction techniques with resulting substantial economies.

It is to be understood that the form of the invention herein disclosedand described is to be taken as the preferred embodiment of the same,and that various changes in the size, shape and arrangement of parts maybe practiced without departing from the spirit of the invention or thescope of the subjoined claims.

I claim as my invention:

1.. A method of making ball studs, comprising providing a blankof'predetermined length and diameter, first forming upon said blankstem, taper and shank portions and a substantially semi-circular headportion, then re straining said head portion against movement in onedirection while displacing the central portion of said head portion inan opposite direction to form therewithin a generally thimble-shapedcavity, and next applying a shaping force to the exterior of the headportion to form said head portion into a substantially round ball shapehaving interiorly thereof a generally circular cavity.

2. A method of making a ball stud provided with'a generally round headand shank, taper and stem portions of lesser'diarneters, comprisingproviding an unheated blank of predetermined length and diameter, firstforming upon said cold blank within a die having a stepped cavity thestern, taper and shank portions and a substantially semi-circular headportion, then restrain-ing said head portion against movement in onedirection while displacing the central portion of said head portion inan opposite direction to form therewithin a substantially thimbleshapedopen-ended cavity, and next forming the head into a substantially roundball shape having interiorly thereof a generally circular lubricantcavity.

3. A method of making a ball stud provided with a generally round headand shank, taper and stemportions of lesserdiameters, comprisingproviding an unheated blank of predetermined length and diameter, firstforming upon said cold blank within a die having 'a stepped cavity thestem, taper and shank portions and a substantially semicircular headportion, then restraining said head portion against movement in onedirection while displacing the central portion of said head portion inan opposite direction to form therewithin a thimble-shaped cavity openat one end thereof, and next essentially entirely closing said cavity byforming the head into a substantially round ball shape having interiorlythereof a generally circular lubricant cavity and a passage leadingthereto.

4. A method of making a ball stud provided with a generally round headand shank, taper and stem portions of lesser diameters, comprisingforming a cold blank of predetermined length and diameter, first formingupon said cold blank the stern, taper and shank portions and asubstantially semi-circular head portion, then forming a substantiallyconcave recess with-in the head portion generally centrally thereof,next restraining said head portion against movement in one directionwhile displacing the central portion of said head portion in an oppositedirection to form therewithin a generally thimble-shaped open-endedcavity, and thereafter forming the head into a substantially round ballshape having interiorly thereof a generally circular lubricant cavity.

5. A method of making a ball stud provided with a generally round headand shank, taper and stem portions of lesser diameters, comprisingproviding a substantially cylindrical blank of predetermined length anddiameter, directing a first punch member against one end of said blankto force said blank entirely within a die having a cavity of varyingdiameter to form thereon the stern, taper and shank portions and asubstantially semi-circular head portion, restraining said head portionagainst move-r ment in one axial direction while directing a secondpunch member against said head portion to displace the central portionof said head portion in an opposite axial direction forming therewithina generally thimble-shaped cavity open at one end thereof, and directingagainst said head portion a die member having a generally concaveshaping surface to form the head portion into a substantially round ballshape having interiorly thereof a generally circular lubricant cavity.

6. A method of making a ball stud provided with a generally round headand shank, taper and stem portions of lesser diameters, comprisingproviding a substantially cylindrical blank of predetermined length anddiameter, directing a first punch member against one end of said blankto force said blank entirely within a die having a cavity of varyingdiameters to form thereon the stern, taper and shank portions and asubstantially semi-circular head portion, moving 'a second punch memberagainst said head portion generally centrally thereof to form. a concaverecess therein, restraining said head portion against movement in oneaxial direction while directing a third punch member into the concaverecess to displace the central portion of said head portion in anopposite axial direction forming therewithin a generally thimble-shapedcavity, and directing against said head portion in surrounding relationthereto a die member having a generally concave shaping surface to formthe head into a subr stantially round ball shape having interiorlythereof a generally circular lubricant cavity.

7. A method of making a ball stud provided with a generally round headand shank, taper and stem portions of lesser diameters, comprisingforming a substantially cylindrical blank of predetermined length anddiameter, directing a first punch member against one end of said blankto force said blank entirely within a die having a cavity of varyingdiameters to form thereon the stem, taper and shank portions and asubstantially semi-circular head portion, locating the partially shapedstud in a die having a cavity conforming at one end to the outerdiameter of the substantially semi-circular head portion but of greaterdepth than the length of said head portion for restraining said headportion against movement in one axial direction, moving a second punchmember against said head portion to displace the central portion of saidhead portion in an opposite axial direction and to form therein agenerally thimble-shaped open-ended cavity, and

directing against said head portion in surrounding relation thereto -adie member having a generally concave shaping surface to form the headinto a substantially round ball shape having interiorly thereof agenerally circular lubricant cavity.

8. A method of making a ball stud provided with a generally round headand shank, taper and stem portions of lesser diameters, comprisingproviding substantially cylindrical blank of predetermined length anddiameter, directing a first punch member against one end of said blankto force said blank entirely within a die having a cavity of varyingdiameters to form thereon the stem, taper and shank portions and asubstantially semi-circular head portion, locating the partially shapedstud in a die having a cavity conforming at one end to the outerdiameter of the substantially semi-circular head portion but of greaterdepth than the length of said head portion for restraining said headportion against movement in one axial direction, moving a second punchmember against said head portion to displace the central portion of saidhead portion in an opposite axial direction and to form therein agenerally thimble-shaped open-tended cavity, supporting the partiallyshaped stud in a die with the head portion extending partially outwardlytherefrom, and directing against said head portion in surroundingrelation thereto a die member having a generally concave shaping surfaceto form the head into a substantially round ball shape having interiorlythereof a generally circular lubricant cavity.

9. A method of making a ball stud provided with a generally round headand shank, taper and stem portions of lesser diameters, comprisingforming a substantially cylindrical blank of predetermined length anddiameter, directing a first punch member against one end of said blankto force said blank entirely within a die having a cavity of varyingdiameters to form thereon the stem, taper and shank portions and asubstantially semi-circular head portion, locating the partially shapedstud in a die having a cavity conforming at one end to the outerdiameter of the substantially semi-circular head portion but of greaterdepth than the length of said head portion for restraining said headportion against movement in one axial direction, moving a second punchmember against said head portion to displace the central portion of saidhead portion in an opposite axial direction and to form therein agenerally thimble-shaped open-ended cavity, supporting the partiallyshaped stud in a die with the head portion extending partially outwardlytherefrom, and directing against said head portion in surroundingrelation thereto a die member having a generally concave shaping surfaceto turn the walls of the head portion radially inwardly and form thehead into a substantially round ball shape having interiorly thereof agenerally circular lubricant cavity.

10. In a method of forming a ball stud from a metal rod of constantcross-section initially, the steps of forming a segmental spherical headportion at one end thereof, restraining said head poriton againstmovement in one direction while displacing a central portion of saidhead portion laterally and axially in an opposite direction to form anextended wall portion, and die forming said extended wall portion to agenerally spherical contour complementing the segmental sphericalcontour of said head portion.

11. In a method of forming a ball stud from a metal rod of constantcross-section initially, the steps of forming a segmental spherical headportion at one end thereof, displacing a central portion of said headportion lateral-' ly and axially in one direction while confining thesegmental spherical surface of said head portion against movement an anopposite axial direction to form an extended wall portion, and dieforming said extended wall portion to a generally spherical contourcomplementing the segmental spherical contour of said head portion.

of, supporting said headipprtion-against movement in one axial directionwhile directing a punch member into, said: segmental sphericalaheadrportion wand displacing a central portion of said headgportion laterallyand axially in an opposite directiontd-for-m a generally cylindricalextended wall portion, and die forming said extended wall portion to agenerallyspherical contour complementing the segmental spherical contourof said head portion.

--References Citediin thefilegof this patent UNITEDJFSTAIES PATENTS'Cayleyetal h Nov. 20, 1894 Kingston May 14, 1918 'Anderson June 13,1922 Skillman June'13, 1933 Purtell Oct. 23, 1934 Peo Apr. 20, 1937Huiferd et al Dec. 9, 1941 Flu-merfelt June 5, 195-1 Latzen Dec. 20,1955 Kaul June'S, 1956

